Win Med Player wont play mpgs correctly

Quick run down on the problem: My WMPv10 wont type files correctly, specifically a video file that is supposed to be 10 minutes long will play but WMP indicates that it is only 30 seconds long. as a result it will only play the first 30 seconds normally and the remaining 9 minutes will play completly off wack...the sound and video wont match up and the image frame is updated once every few seconds. Incidently a 20 minute video ends up being a 60 video according to WMP. The files themselves arnt damamged...its every file that is .mpg only. I have burnt the file onto a CD and it plays fine on my other comps. I also have a WiFi network and can play all the files from my other computers, just not my Dell700m

Details:
Computer w/ problem: Dell700m w/ XP pro SP2, WMPv10.3646

Might be a codec problem.Install the ACE Mega codecS pack,available here.

Upgrade to the latest version (build 3923).

In WMP,go to Tools > Options > File Types and make sure "mpeg" is checked.